SU1495309A1 - Method of treating waste water - Google Patents

Abstract

The invention relates to methods for treating wastewater from a hydrolysis plant by autoclaving and allows for simplifying the purification process by lowering the temperature and shortening the process, as well as reusing the autoclaved effluent from the hydrolysis plant. The method is carried out at 170-190 ° C for 0.5-3 hours, then, without cooling the autoclave, the pressure is reduced to atmospheric pressure and the precipitate is filtered off. The process is conducted without adjusting the PH medium before and after autoclaving. The COD of the purified water is 40-50 g / l, while the volatile organic compounds are completely removed from it. 3 tab.

Description

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The invention relates to wastewater treatment methods and can be used in hydrolysis plants. closed cycle water use.

The purpose of the invention is to simplify the process and provide the possibility of reusing wastewater from a hydrolysis production.

In order to carry out the process, the wastewater is held in an autoclave for 0.5-3 hours at 170-190 ° C and an initial pH of wastewater 1-5, followed by the removal of vapor-containing volatile organic compounds and filtering the resulting solid residue.

Example 1. In a titanium autoclave with a capacity of 50 ml, 45 mp of wastewater of composition are supplied,%: dry substances -. 18, including mineral 10;

suspended solids 0.14, furancarboxylic acid 0.38; hydroxymethylfuran-carboxylic acid 0.17; pH 4.0; COD 120 g.

The autoclave is rapidly heated to 180 ° C, the time specified in Table 1 is maintained, the pressure is reduced to atmospheric. In this case, volatile organic substances are removed with steam, after which the solid residue is separated by filtration. In tab. 1 shows the dependence of the composition of wastewater from the heating time.

From the obtained data it follows that the optimal heating time is 0.5-3 hours. With a time less than 0.5 hours, the process does not have time to start, more than 3 hours - the amount of residue decreases and the degree of purification decreases.

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2. Cleaning is carried out

Example as in example 1. Heating time 1 hour, temperature.

The dependence of the composition of wastewater on the change in pH is given in Table. 2

Thus, the initial pH value of wastewater (within 1-5) does not affect the purification process, for which reason it does not require an extra complicating process, the stage of preliminary neutralization.

PRI me R 3. The purification was carried out as in Example 1. The heating time was 1 hour, pH 4.0.

The dependence of the composition of wastewater on the heating temperature is given in table.3.

Thus, the optimum heating temperature is 170-190 ° C. At temperatures below 170 ° C, the process does not occur, and the degree of purification is insufficient and the amount of soluble toxic substances — secondary products of wood destruction — which prevent the reuse of autoclaved waste for growing yeast, increases sharply.

Example 4 Carried out by a known method. In a titanium autoclave with a capacity of 50 ml. 45 ml of the waste water of the composition according to example 1 is fed in and neutralized. The autoclave is heated rapidly and held for 2.5 hours at 250 ° C. At the end of the process, the waste water is cooled to room temperature.

The composition of the resulting wastewater,%: dry matter 16.0; furancar

0.13 0.00 0.00 0.00 0.00

boic acid 0,00; hydroxymethylfurancarboxylic acid 0.00-, the residue 0.6j pH 9.0; COD 92 g / l.

Example 5. Carried out by a known method. The process is carried out according to the conditions of Example 4, at the end the solution is acidified to pH 3.0.

After acidification, the composition of the waste water: solids 15.8%, an additional 0.2% of the residue is formed, the COD is 89 g / l.

The use of the proposed method allows to simplify the cleaning process and use the waste water after treatment in an autoclave for reuse in closed loop hydrolysis plants. The COD of purified water is 40 to 50 g / l, while the volatile organic compounds are completely removed from it.

Claims (1)

Invention Formula A method of purifying wastewater from organic compounds, including heating the wastewater in an autoclave, holding it at a constant temperature, reducing the pressure to atmospheric and then separating the phases, characterized in that, is carried out at 170-190 ° C for 0.5-3 hours, and the pressure is reduced to atmospheric pressure without pre-cooling the autoclave, and the phase separation is carried out by filtration. Table 1 Compiled by L. Ananiev. Editor N. Yatsola Tehred A. Kravchuk. Corrector .Shekmar Order 4206/22 Circulation 828 VNIIPI State Committee on Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, 4/5 Raushsk Nab. Production and publishing plant Patent, Uzhgorod, st. Gagarin, 101 Subscription